1. Field of the Invention
This invention relates to a wiring material which is, for example, used in a harness for a car and a method for manufacturing the same.
2. Background Art
Generally, as a flexible wiring material for use in a vehicle, there is known a flat cable composed of a plurality of flat conductors (for example, rectangular conductors) arranged in the width direction thereof and covered by an insulating-material. Such flat cable has various advantages: for example, it is small in thickness and excellent in flexibility as well as, because it can be curved, the direction thereof can be changed freely.
As means for securing the current capacity of the rectangular conductor, there are available several means; for example, means for increasing the width of the rectangular conductor, means for increasing the number of rectangular conductors and making a circuit using a plurality of rectangular conductors, and means for increasing the thickness of the rectangular conductor to thereby increase the section area of the rectangular conductor.
By the way, in the case of a flat cable, a terminal is connected to the end portion of the flat cable and the thus connected terminal is fitted with a connector to thereby form a wiring material; and, the thus-formed wiring material is connected to an apparatus such as a motor. As the connector to be fitted with the terminal, it is preferred to use an existing connector and, therefore, in the flat cable, the arrangement pitch and width of the rectangular conductors must be designed so as to conform to an existing terminal.
In case where the width of the rectangular conductor is increased in order to secure the required current capacity, the design of the connector must be changed greatly so as to correspond to the thus increased width of the rectangular conductor. In this case, however, the flat cable including the width-increased rectangular conductor cannot be connected to the existing terminal. Also, in case where, in order to secure the current capacity of the rectangular conductors, the number of rectangular conductors is increased and a plurality of rectangular conductors are allotted to one circuit, the widths of the connector and flat cable must be increased, which makes it necessary to change the shape of the existing connector. Further, in case where, in order to secure the current capacity of the rectangular conductor, the thickness of rectangular conductors is increased, the thickness of the flat cable is increased accordingly to thereby lower the flexibility of the flat cable, with the result that the flat cable is not be able to fulfill its original function.
As a method for solving the above problems, there is known a method which is disclosed in Japanese Patent Application, First Publication Nos. Hei.3-4464 and Hei.3-4465.
That is, in the above-cited publication, there is disclosed a method in which, as shown in FIG. 16, the width of a flat cable is increased to thereby increase the width of rectangular conductors included in the flat cable so as to secure the required current capacity of the flat cable; and, the leading end portion of the flat cable is drawn or narrowed so as to conform to the pitch width of the cavity of an existing connector, and the flat cable is then connected to the existing connector. However, in case where the end portion of the flat cable is drawn in this manner, there arise not only a problem that the current capacity of the flat cable is limited and thus a desired current is not allowed to flow, but also a problem that the resistance of the drawn portion increases and thus heat is generated in the drawn portion. Also, in case where such drawn portion is formed in the flat cable, the dimension of the flat cable cannot be adjusted at an arbitrary position, which makes it impossible to produce the flat cable continuously.
Moreover, since the flat cable disclosed in the above-cited publication is quite irregular in the shape of the end portion thereof, continuous manufacture of the flat cable is substantially impossible: that is, the flat cable is poor not only in the mass productivity but also in the yield rate.
The present invention aims at eliminating the drawbacks found in the above-mentioned wiring materials. Accordingly, it is an object of the invention to provide a wiring material in which not only the widths of the main body portions of the respective conductors thereof can be expanded to thereby increase the current capacity thereof but also, without reducing the mass productivity and yield rate thereof, the terminal end portions of the respective conductors can be matched to terminals to be connected to the respective conductors, and a method for manufacturing such wiring material.
It is another object of the invention to provide a wiring material structured such that not only flat cables thereof can be formed so as to conform to an existing connector while securing the required current capacity thereof but also the flexibility of the flat cables are not degraded.
In attaining the above object, according to a first aspect of the invention, there is provided a wiring material comprising a plurality of flat cables, each of the plurality of flat cables including a plurality of conductors arranged in the width direction thereof and an insulating body for covering the outer surfaces of the respective conductors, wherein the respective conductors of the respective flat cables include in the end portions thereof terminal fixing portions formed smaller in width than the main body portions of their respective conductors for fixation of connecting terminals thereto, and the plurality of flat cables are superimposed on top of one another in the thickness direction thereof in such a manner that the terminal fixing portions are shifted in position from one another in the width direction thereof and are thereby arranged at the same pitch as the arrangement pitch of the connecting terminals.
According to the present structure, simply by superimposing a plurality of flat cables on top of one another, each flat cable including terminal fixing portions formed in the end portions of the respective conductors, the terminal fixing portions can be arranged in the width direction thereof at the same pitch as the connecting terminal arrangement pitch. Therefore, while not only expanding the widths of the main body portions of the respective conductors but also preventing the end portions of the conductors of the respective flat cables from being formed in irregular shapes, the end portions of the present conductors and their respective connecting terminals can be matched together.
Here, the concrete formation positions of the terminal fixing portions in the respective flat cables are not limitative but the flat cables may be superimposed on top of one another in such a manner that the terminal fixing portions can be finally arranged at a given terminal arrangement pitch. For example, there can be employed a structure in which the flat cables are set equal to one another in the number and arrangement pitch of the conductors and, between the flat cables, the formation positions of the terminal fixing portions of the respective conductors are shifted from one another in the width direction thereof by the above-mentioned connecting terminal arrangement pitch. That is, in this case, by employing flat cables which are equivalent to one another in the basic arrangement thereof, the mass productivity thereof can be enhanced further and the terminal fixing portions can be arranged at a given arrangement pitch without shifting the flat cable superimposed positions in the width direction thereof from one another.
Therefore, by fixing the connecting terminals to the their respective terminal fixing portions of the present wiring material, there can be easily obtained a wiring material with a connector in which the connecting terminals are inserted into the common connector housing in such a manner that they are arranged at the above-mentioned arrangement pitch.
By the way, since the respective terminal fixing portions are smaller in width than the main body portions of the conductors, especially in the case of a high voltage, there is a fear that heat can be generated locally in the respective terminal fixing portions. However, in case where there is employed a structure in which a plurality of conductors are superimposed on top of one another in the end portions of the flat cables including the terminal fixing portions, although the terminal fixing portions are set small in width, the terminal fixing portions are allowed to secure section areas substantially equivalent to the main body portions of the conductors, which can prevent the above-mentioned local heat generation in the respective terminal fixing portions.
Also, according to a second aspect of the invention, there is provided a method for manufacturing a wiring material with a connector structured such that a common connector is disposed in the end portions of a plurality of flat cables, the method comprising the steps of: forming, in the end portions of the respective conductors of the flat cables, terminal fixing portions smaller in width than the main body portions of the respective conductors; superimposing the plurality of flat cables on top of one another in such a manner that the terminal fixing portions thereof are shifted in position from one another and are thereby arranged at a given pitch; and, inserting and fixing the connecting terminals to a common connector housing in such a manner that the connecting terminals are arranged at the above-mentioned pitch.
According to the present method, with use of a simple arrangement in which the flat cables with the terminal fixing portions formed therein (that is, the flat cables that do not require irregular shapes specially) are simply superimposed on top of one another, the terminal fixing portions can be arranged at a given terminal arrangement pitch, and the connecting terminals fixed to the present terminal fixing portions, as they are, can be inserted into a common connector housing with no inconvenience.
Here, the step of superimposing the plurality of flat cables on top of one another may be executed before the step of fixing the connecting terminals to their respective terminal fixing portions, and vice versa.
Also, the terminal fixing portion forming step may also comprise the steps of: removing an insulating material disposed on one-side outer surfaces of the end portions of the flat cables; forming, at least in part of the insulating material removed areas, small-width portions smaller in the conductor width than the remaining portions of the flat cable end portions; and, turning back the flat cables in the present small-width portions and superimposing the conductors on top of one another. In this case, there can be easily obtained terminal fixing portions in which a plurality of conductors are superimposed on top of one another, that is, terminal fixing portions which are formed small in width but are able to secure sufficient section areas.
Another aspect of the invention is a wiring material, comprising: a first flat cable including a plurality of rectangular conductors arranged in the width direction thereof at a given pitch, the outer peripheries of the rectangular conductors being covered with an insulating body; a second flat cable including one or two rectangular conductors, the outer peripheries of the rectangular conductors being covered with an insulating body, the second flat cable being superimposed on the first flat cable in such a manner that the rectangular conductor(s) of the second flat cable is (or are) superimposed on top of any one of the rectangular conductors of the first flat cable in the width direction thereof, wherein the end portions of the rectangular conductors of the mutually superimposed first and second flat cables are connected to a common terminal.
According to the present structure, since the first and second flat cables are connected to the common terminal in such a manner that the conductors of the first and second flat cables are superimposed on top of one each other, there can be obtained the current capacity that is required by a circuit to which the terminal is to be connected, without increasing the width dimensions of the flat cables. On the other hand, because it is not necessary to fix the middle portions of the first and second flat cables to each other and thus the first and second flat cables can maintain their states that they can be flexed and deformed independently of each other, differently from a structure in which the thickness of the conductors is increased, there is no fear that the flexibility of the whole wiring material can be degraded. Also, since the respective rectangular conductors are arranged at a given pitch, they can be fitted with an existing connector.
Also, according to another aspect of the invention, a plurality of second flat cables are superimposed on top of at least one of the rectangular conductors of the first flat cable. According to this structure, by superimposing a plurality of rectangular conductors of the second flat cable on top of the rectangular conductors of the first flat cable, there can be obtained the current capacity that is required by a circuit to which the terminal is to be connected.
Further, according to another aspect of the invention, the second flat cables include a flat cable structured such that a plurality of rectangular conductors are arranged in the width direction thereof at the same pitch as the pitch of the first flat cable. According to this structure, since the pitch of the rectangular conductors of the first flat cable is set equal to the pitch of the rectangular conductors of the second flat cable, although the second flat cable includes a plurality of conductors, the respective conductors can be superimposed on top of the rectangular conductors of the first flat cable. Also, because the second flat cable includes a plurality of rectangular conductors, the number of the second flat cables can be reduced.
And, according to another aspect of the invention, each of the second flat cables includes a single rectangular conductor and a required number of second flat cables are superimposed on top of the respective rectangular conductors of the first flat cable. According to this structure, as the second flat cable, flat cables having the same structure can be mass produced and the required number of flat cables may be used according to the required current capacity, which can enhance the productivity of the second flat cable.
Also, according to another aspect of the invention, the terminal is a pressure mounting terminal including embracing pieces, and the pressure mounting terminal is pressure mounted on the mutually superimposed rectangular conductors in such a manner that the embracing pieces embrace the end portions of the superimposed rectangular conductors. According to this structure, using a simple structure in which the end portions of the conductors of the first and second flat cables are embraced by the embracing pieces of the pressure mounting terminal, the end portions of the conductors can be connected to the terminal as an integral unit. Also, there is no need to remove the insulating bodies for covering the end portions of the conductors, which can enhance the productivity of the flat cables.
According to another aspect of the invention, in a wiring material as set forth in any one of the first to fourth aspects of the invention, the insulating bodies disposed on the end portions of the respective flat cables for covering the same are removed therefrom to thereby expose the end portions of the rectangular conductors of the flat cables, the superimposed rectangular conductors are superimposed on top of connecting portions formed in the terminal, and, in this superimposed state, they are connected together as a unit. According to this structure, since the connecting portion of the terminal is welded and connected to the exposed rectangular conductors of the first and second flat cables, strong connection can be realized between the terminal and flat cables.